Some degree of positive illusion seeing virtues in partners that they do not see in themselves is critical for sustaining satisfying dating and marital relationships. The proposed experiments examine the mechanisms linking self-esteem to positive illusions and relational well-being. Study l tests the hypothesis that low self-esteem (LSE) disrupts idealization because self-doubt breeds unwarranted insecurities about a romantic partner's affection. Dating individuals in the experimental conditions will first complete a considerateness questionnaire and then receive feedback suggesting they are behaving either considerately or inconsiderately. Control participants will not receive feedback. Dependent measures tapping perceptions of the partner's regard, fears of rejection and positive illusions will then be administered. Studies 2 through 5 test the related hypothesis that a more conditional sense of self breeds LSE intimates' insecurities and leaves them more vigilant for signs of a partner's (anticipated) rejection. Study 2 tests the hypothesis that seeing others' acceptance as conditional links self-doubt to relationship insecurities, whereas seeing others' acceptance as unconditional facilitates the use of the relationship as a self-affirmational resource. Dating individuals in Study 2 will first visualize someone who accepts them conditionally or unconditionally. Individuals in the self-threat condition will then perform poorly on a memory test. Control participants will not experience this failure. The dependent measures used in Study l will then be administered. Study 3 will replicate Study 2 using a relationship- based threat to self-esteem (i.e., feelings of guilt over a past transgression). Study 4 tests the hypothesis that merely priming conditionality activates self-doubts and leaves LSE intimates less confident of their partners' regard. Dating individuals in the conditionality condition will list 10 reasons why their partners care for them. Individuals in the self-focus control condition will list 10 qualities they like about themselves. Dependent measures tapping reflected appraisals, idealization and state self-esteem will then be administered. Study 5 tests the reverse hypothesis that priming self-doubt activates concerns about conditionality for LSE individuals. Participants will first list either an easy or a difficult number of their own virtues or faults to differentially prime self-doubt. Measures of reflected appraisals and perceived conditionality of the partner's regard will then be administered. Apart from shedding light on the dynamics of self-regulation in romantic relationships, this research might also facilitate the development of clinical interventions, such as fostering more accurate understandings of a partners positive regard and unconditional acceptance, that might circumvent LSE individuals' relationship-defeating thought patterns.